Expendable case ammunition



Dec. 23, 1969 J. J. SCANLON EXPENDABLE CASE AMMUNITION Filed Nov. 29. 1967 Inventar: John J. Scahlon e. Hm

Mim V. .A

w Qttarneys United States Patent Ofiice 3,485,170 Patented Dec. 23, 1969 US. Cl. 10233 13 Claims ABSTRACT OF THE DISCLOSURE A cartridge for firearms having a plastic body open at both ends and having a web closing the interior adjacent one of the open ends. One of the open ends is formed to hold a projectile while either a combination of loose powder propellant and a solid propellant cup or a solid propellant is contained in the opposite end. The end containing the propellant is closed by a molded or solid primer which is formed in an opening in either the solid propel lant or the solid propellant cup. Upon firing, the case as well as the projectile is completely expelled from the muz zle of the firearm.

This invention relates to cartridges for firearms and particularly to cartridges having cases designed to be expelled from the muzzle of the firearm along with the projectile as a result of the action of the gases generated by the burning propellant.

The subject invention contemplates forming a cartridge of suitable thermoplastic cases by injection molding. The case is formed substantially in the shape of a cylinder having both its ends open with a solid web closing the interior of the cylinder adjacent the muzzle end of the case. The web has a cavity formed therein opening toward the muzzle end of the case but it can be formed with a small opening completely therethrough, The general cross-section of the cylinder is substantially the same as the crosssection of a conventional brass case except for the presence of the web which is not found in conventional cases, and the absence of a head or rim usually provided on metal cases. The muzzle end is tapered and provided with a cavity to hold the projectile. The opposite or breech end is open and is formed to hold either a solid or loose granular propellant. With either type of propellant -asolid primer composition is provided adjacent the open or breech end of the case and is covered by a disc of foiling paper or other suitable material and the case is sealed or closed by a plastic film or coating over the breech end of the case to make the cartridge waterproof.

In recent years considerable effort has been expended to develop so-called caseless ammunition. These etTorts have resulted in some cartridges made with solid propellants which are much lighter and occupy less volume than conventional brass or other metal case cartridges. The lack of a case to extract makes them extremely desirable for use in armored vehicles where space is at a premium. Such a cartridge should provide more reliable operation of automatic weapons because there is no case to extract. A large number of the jams occurring in such weapons are caused by the trouble in extracting and ejecting metal cases. It should also be possible to manufacture such cartridges at a lower cost than conventional cartridges.

There are many disadvantages and defects in caseless cartridges which as yet have not been overcome. They are not waterproof, are structurally weak, and are susceptible to ignition due to cigarettes, cook-ofi in a hot chamber and the like. The solid propellant for such cartridges, has a tendency to break-up when being handled or loaded, particularly in an automatic firearm. At the present time dimensional control of the propellant is dilficult and costly to attain and must be done by grinding or machining.

The present velocities available in conventional ammunition are limited by the pressure that can be contained safely by the cases. In either a caseless or plastic expendable case cartridge the pressure and consequently the velocity is not limited by the strength of a metal case. It has long been known that firearms can be constructed which will be able to withstand much higher pressures than brass cases.

The instant invention provides an expendable plastic cartridge case which is expelled from the muzzle of the firearm along with the projectile. The plastic case protects the propellant from moisture, cook-off and breaking away from the projectile. A cartridge with such a case is only a very slight bit heavier than a caseless cartridge. The use of such a case allows the use of either solid or granulated propellants.

It can thus be seen that the major object of this inventron is to provide a cartridge with substantially all the advantages of a caseless cartridge and none of the disadvantages thereof.

Another object of this invention is to provide a cartridge having a case which is expelled through the muzzle of a firearm.

Still another object of this invention is to provide a cartridge that protects the propellant from its environment but leaves no case in the firearm chamber to be extracted after firing.

A further object of this invention is to provide a cartridge that has a case which provides a thermal barrier against accidental ignition and provides sufiicient strength for use in automatic firearms while leaving no case to be extracted after firing.

A still further object of this invention is to provide a cartridge with a case of plastic material so that the cartridge weight is substantially the same as that of a caseless cartridge.

A still further object of this invention is to provide a cartridge which will propel the bullet at higher velocities with lower propellant charges due to higher pressures possible with expendable cases.

In the drawings:

FIGURE 1 is a sectional side elevation of the expendable case for the ammunition which is the subject of this invention;

FIGURE 2 is a side elevation of the expendable case cartridge loaded with solid propellant;

FIGURE 3 is a side elevation of the expendable case cartridge loaded with loose propellant and a molded propellant cup combination; and

FIGURE 4 is a side elevation of the expendable case cartridge loaded in the chamber of a firearm.

The drawings illustrate an expendable case cartridge which is of the centerfire small arms type. The principles of this invention will apply to expendable case ammunition of all sizes and this invention is not limited to small arms ammunition only.

In the drawings an expendable cartridge case 1 is shown in FIGURE 1. It can be seen that case 1 is generally similar to metal cases currently used for ammunition of the centerfire or artillery type. In order to provide for propellant and projectile, case 1 is formed with a first chamber 2 to hold the propellant charge and a second chamber 3 to hold the projectile. A solid web 4 is provided between chambers 2 and 3 and is formed integral therewith. An opening or cavity 5 is formed in web 4, the purpose of which will be explained later.

Chamber or cavity 3 is formed internally to correspond to the shape of the projectile that is loaded in case 1. The inside diameter of chamber 3 is designed to receive the projectile by.anv interference fit or a loose fit if the projectile is secured by an adhesive. The sidewall 6 at the mouth of chamber 3 is relatively thin while the remainder of the case adjacent chamber 3 tapers outwardly to the dimensions of chamber or cavity 2. The sidewall 7 of chamber 2 is relatively thin for most of its length, however, the section of chamber 2 adjacent web 4 is formed with a radius as shown in FIGURE 1. The purpose of this radius will be set forth below.

It can thus be seen that case 1 is generally the same shape or configuration as conventional brass cartridge cases. There are, however, some very important differences in the two types of cases. The expendable case is made of a thermoplastic resin and it has been found that injection molded polycarbonate cases work extremely well. Low viscosity polycarbonate resins which are used for molding intricate hard to fill parts have been found to work very well in making expendable cartridge cases. Also the expendable case includes web 4 between the propellant cavity and the projectile cavity. In addition, case 1 is shown with straight outer sides and tapered internal sides for the propellant cavity and is open at the rear with no rim or head that is a part of brass cases.

While it is known that molded polycarbonate cases work and will always be expelled with the projectile, other thermoplastic materials will also make suitable cases. It is necessary for the case to have sufficient strength to remain intact as it starts down the bore of the barrel. Once the entire case has entered the bore the gases will expel it from the muzzle even if it breaks up in the bore. When the cases separate in the chamber usually some piece remains in the chamber. This happens if the case is made of low density polyethylene, however, if the case is made from a slug of polyethylene by a cold molding process the strength is increased due to biaxial orientation a point where the case will remain intact at least until it enters the bore and will, therefore, be completely expelled from the muzzle.

It is also possible to make polyethylene cases by forming an oriented tube in the form of sidewall 7. This tube can be made by any of the known methods of producing oriented shotshell bodies. The oriented tube can then be inserted into a mold cavity and the remainder of the case can be injection molded to the oriented sidewall section. A case of polyethylene formed in such a manner has sufficient strength to be expelled from the muzzle by the action of the gases produced by the burning propellant.

Case 1 is shown with smooth sides but if necessary for extraction purposes a rim or detent can be molded on case 1 or a groove or indent can be provided to be engaged by an extractor. With a smooth case, a bolt can be provided with an extractor that will grip the case by a squeezing action if it is necessary to extract an unfired cartridge. With case 1 made of plastic the cartridge will slide out of the chamber if the firearm is in a vertical position with the muzzle up and the bolt open. This method can always be used as an alternate means of ejecting an unfired expendable cartridge.

FIGURE 2 shows a loaded round of ammunition utilizing an expendable case. A projectile or bullet 8 is mounted by means of adhesive or a friction fit in chamber 3 completely filling chamber 3 and extending forward of sidewall 6. In this particularly version, a charge of solid molded propellant 9 is held in chamber 2 by an adhesive or by means of an interference fit and the rear end of propellant 9 is flush with the end of sidewall 7. Any suitable solid or molded primer composition 10 is secured by friction or other means such as an adhesive in a pocket formed in the rear end of propellant 9. Primer 10 is covered by foiling paper and the propellant primer assembly is sealed by a thin film of suitable plastic 11 which can either be fastened with an adhesive to case 1 or heat sealed to case 1. It is also possible to insert mold case 1 to projectiles when case 1 is formed by molding.

A cartridge loaded with granular or loose propellant 12 is shown in FIGURE 3. This cartridge is almost the same as the cartridge shown in FIGURE 2, however, the end of sidewall 7 has a reduced section 13 to accommodate a molded propellant primer cup 14 which is glued to section 13. Cup 14 is provided with a pocket to hold primer 10. Loose propellant 12 is held in case 1 by means of cup 14 and the assembly is sealed by plastic 11.

The propellant means, whether it is solid molded propellant 9, loose propellant 12, or a molded propellant primer cup 14, along with the primer 10, is made of consumable or combustible material which is substantially entirely consumed or used up upon firing so that no portion of the propellant or the primer remains in the gun chamber after firing of the cartridge.

While the drawing shows chamber 2 only partially filled with either solid or loose propellant cartridges can be loaded so that either type of propellant will completely fill chamber 2. The desired ballistics for projectile 8 will govern the amount of propellant loaded in chamber 2.

One suitable way of securing primer 10 in the pocket formed in propellant 9 or cup 14 is to actually mold the primer in the pocket. This is accomplished by placing loose primer composition in the pocket and compressing it in place. When the primer is molded in the pocket it is compressed to such a degree that it does not completely fill the pocket and as shown is recessed slightly inward from the end of the solid propellant in which it is placed. If the primer is molded first and then inserted in the pocket it is shaped so that it will be recessed from the end of the solid propellant in which it is placed. The solid propellant 9 or cup 14 provides the necessary backup for primer 10 so that it will ignite when struck by a firing pin.

The cartridge shown in FIGURE 3 is shown in a firearm chamber 15 in FIGURE 4. The cartridge is prevented from sliding down the barrel by the chamber configuration which corresponds to the outside shape of case 1. The support afforded by the tapered surface of the firearm chamber bearing against the tapered shoulder of the case is necessary to furnish support for the primer so that the primer will fire when struck by the firing pin. Upon firing projectile 8 and case 1 both will attempt to move down the bore 16 of barrel 17. Because they both cannot enter the same area at the same time, bullet 8 will enter bore 16 before case 1 will. Cavity 5 allows web 4 to collapse to a degree sufficient to allow the larger case to enter and travel down the smaller bore. Cases with holes completely through web 4 connecting cavities 2 and 3 have worked satisfactorily. Such cases allow web 4 to collapse to a great extent and close the hole when this occurs so that gas will not pass through but will remain behind case 1 to drive it completely through the barrel. The rear section of web 4 is formed with a curvature 18 so that the force of the propellant gases will be equally distributed across the entire web. This distribution of the forces will usually force case 1 out of the muzzle in one piece and insure that the entire case is expelled from the muzzle. While the rear surface of web 4 has been shown with a curvature, other configurations will function satisfactorily. It is preferred that the rear surface of web 4 engage sidewall 7 at an angle greater than Any configuration that distributes the gas pressure more evenly and reduces thrust at the junction of the web and wall will function properly.

While no bolt or firing pin have been shown, any suitable bolt that will seal chamber 15 can be used. It has been found that sealing can be accomplished by means of an O-ring mounted on the outside of the bolt adjacent the face thereof. The firing pin for the cartridge set forth must-be of the stab type.

It has been found that the projectile can be retained in case 1 by means other than gluing. It is possible to provide a friction fit between bullet 8 and sidewall 6. Also, the solid propellant can be retained in' chamber 2 by means of plastic film 11 although it is preferred to secure it by means of an adhesive. It is necessary to have such film .or coating to make the cartridge waterproof and fireproof as well as protecting the solid propellant from breaking up when handled or when in a firearm.

The drawings show cavity 5 communicating with chamher 3, however, cavity 5 can be formed so that it communicates with chamber 2. As previously stated, the purpose of cavity 5 is to allow web 4 to collapse when case 1 enters the bore of the barrel. As long as a cavity is formed in web 4 it does not matter in which side of the web the cavity is formed.

What is claimed is:

1. An expendable cartridge comprising a case made of deformable plastic material having a transverse wall integrally formed therewith to define an open-ended propellant chamber at its breech end and an open-ended projectile chamber at its mouth end, said cartridge case being of maximum diameter adjoining said propellant chamber and of minimum diameter adjoining said projectile chamber, projectile means at least partially positioned in said projectile chamber and secured therein, propellant means positioned in said propellant chamber and secured therein, priming means positioned in and secured to said propellant means, said propellant means and said priming means being substantially entirely consumed upon firing, whereupon said plastic cartridge case is deformed and forced out of the gun barrel behind the projectile means thus resulting in the entire cartridge being expelled from the gun, said propellant means comprising a first propellant portion positioned in said propellant chamber, and a second solid, unitary propellant portion which is secured to the breech end of said case to close ofi said propellant chamber, said priming means being positioned and secured to a recess in said second, solid, unitary propellant portion.

2. An expendable cartridge as recited in claim 1 in which sealing means are provided which protect said propellant and priming means from the environment and other hazards.

3. An expendable cartridge firing system in which a larger diameter cartridge case is expelled, along with a projectile means, through a smaller diameter gun bore, said system comprising a firearm with a gun chamber which opens into a receiver means at one end and into an axially aligned bore at the other end, an expendable cartridge slidably positioned in said gun chamber, means limiting the depth of insertion of said expendable cartridge into said chamber, said expendable cartridge comprising an elongated body member made of deformable plastic material, said body member having a mouth end of smaller diameter than the remaining portion of the body member, projectile means secured in the mouth end of the body member, propellant means, at least a portion of which is formed of a solid unitary unit, and initiating means secured in and closing off the larger diameter, rear end portion of the body member, said cartridge upon being fired causing said initiating means and said propellant means to be substantially entirely consumed thus explosively projecting said projectile means out of said body member and through said bore and also deforming said body member to a smaller diameter so that the body member squeezes down into the smaller diameter gun bore to follow the projectile means through the gun bore and out of the barrel whereupon the body member falls to the ground while the projectile means retains its desired trajectory.

4. An expendable cartridge firing system as recited in claim 3 in which said body member includes an intermediate portion which tapers from the smaller diameter mouth end to the larger diameter rear end portion, said gun chamber having a portion thereof having the approximate configuration and dimensions of the tapered portion of the body member within regular manufacturing tolerances.

5. A firing system as recited in claim 3 wherein said '6 means limiting the depth of insertion of said expendable cartridge comprises an abutment on said gun chamber against which the mouth end of said b dy member abuts when in firing position.

6. A firing system in which the entire cartridge is expelled from the muzzle of a firearm, said cartridge comprising a cartridge case and an associated projectile means, said cartridge case being made of deformable, plastic material and comprising an elongated, generally tubular member having a mouth end and a breech end at the opposite end thereof, transverse wall means integrally formed intermediate said ends to form with said elongated member an open-ended propellant cavity at the breech end and an open-ended projectile cavity at the mouth end, projectile means positioned and secured in said projectile cavity, said propellant cavity having its open end closed Off by a molded, consumable propellant means which is substantially entirely consumed upon firing, consumable ignition means positioned and secured in said propellant means, said firearm from which said cartridge is to be expelled after firing comprising a gun barrel having a bore of lesser diameter than said cartridge case and a gun chamber in which said cartridge is positioned for firing, means abutting said cartridge to limit forward movement of the cartridge into the chamber prior to firing and to give support thereto during firing, said cartridge case adapted to be deformed so as to be entirely expelled through the smaller bore diameter of the gun barrel upon firing without leaving any portion thereof in the gun.

7. A firing system including a gun having a gun barrel with a bore therein and a gun chamber and an expendable cartridge adapted to be positioned in said chamber prior to firing, said cartridge comprising an elongated, open-ended cartridge casing having a front mouth end and a rear breech end, transverse wall means integrally formed with said cartridge casing between said mouth end and said breech end to define a forward projectile cavity and a rear propellant cavity, projectile means secured in said projectile cavity, a solid propellant means closing off said breech end of said cartridge casing and secured thereto, priming means secured to said propellant means, said propellant means and said priming means being made entirely of consumable materials which are used up upon firing of the cartridge, said cartridge casing, upon firing, becoming separated from said projectile means and the entire cartridge casing being expelled from the gun chamber to follow the projectile out of the bore of the gun barrel thus leaving nothing remaining in the gun which must be extracted and ejected.

8. A firing system as recited in claim 7 in which at least a portion of said cartridge casing is biaxially oriented so as to provide added strength.

9. A firing system as recited in claim 7 in which a sealing means is provided over the rear breech end of the expendable cartridge to protect the propellant and priming means from moisture and other hazards.

10. A firing system as recited in claim 7 in which said bore through which said projectile means and expendable cartridge casing are explosively propelled is smaller in diameter than said cartridge casing whereupon said casing must first be deformed and collapsed before it can follow the projectile means through the gun barrel bore.

11. A firing system as recited in claim 10 in which said cartridge casing is made of a polyolefinic material.

12. A firing system as recited in claim 10 in which said cartridge casing is made of a polycarbonate material.

13. An expendable cartridge comprising a case made of deformable plastic material which is not combustible under normal firing conditions, a transverse wall means integrally formed with said case to define an open-ended projectile chamber at its mouth end and an open-ended propellant chamber at its breech end, said cartridge case being of maximum diameter adjoining said propellant chamber and of minimum diameter adjoining said projectile chamber, projectile means at least partially positioned in said projectile chamber and secured therein, propellant means, at least a portion of which is of solid unitary construction, positioned in said propellant chamber so that said solid propellant portion closes off the open end of said propellant chamber, priming means positioned in and secured to said solid propellant portion, said propellant means and said priming means being entirely made of consumable materials so that upon firing said propellant means and said priming means are substantially entirely consumed whereupon said plastic cartridge case is deformed and forced out of the gun barrel behind the projectile means thus resulting in the entire cartridge being expelled from the gun.

References Cited UNITED STATES PATENTS 9/1968 Houdek ROBERT F.

Whitmore 102-42 Haenichen 102-38 Ringdal 102-38 De Caro 102-38 X Larson 102-43 Stadler et a1 102-38 Quinlan 102-38 Metcalf et al. 102-43 FOREIGN PATENTS France; Great Britain.

STAHL, Primary Examiner 

